Climate change, evolution and biodiversity hotspots

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The genetic analysis of marine organisms has revealed various examples of cryptic species: populations of which it was previously thought that they belonged to the same species because they shared the same morphological diagnostic characters.

Genetic comparisons demonstrated that some distant populations were genetically equally different as well separated species. Such studies have generated important new insights into the process of speciation in the marine environment. For example the Heart Urchin, Echinocardium cordatum, has been split into five distinct branches (clades). Such clear-cut genetic distinctions between populations provide strong evidence of reproductive isolation, which implies that speciation has occurred. This means that the species Heart Urchin actually consists of 5 different species.

This phenomenon suggests that genetic and morphological change may take place at different rates in evolution, and that such cryptic species are a product of slow molecular evolution without morphological changes. They provide good models to help understand the speciation processes which lie at the heart of modern evolutionary theory[1].

Climate change and biodiversity hotspots

Along the rocky shores throughout Europe, large, brown seaweeds are a dominant intertidal, foundational species. In subtidal, soft-sediment habitats, this dominant role is played by seagrasses.

Members of the genus Fucus and the seagrass, Zostera marina were extensively sampled throughout their entire North Atlantic ranges. During the last glacial maximum (ca. 18,000 years Before Present) the refugia for most seaweeds and invertebrates were located in parts of SW Ireland, Brittany and NW Iberia. Today, the Brittany peninsula remains a hotspot of this accumulated diversity for many taxa. The biodiversity in NW Iberia however is quickly falling behind as increased sea surface temperatures push species distributions northward.

This type of analysis helps to understand the changes in biodiversity that will occur as nature responds to climate change. Such information can provide detailed information about large scale connections along the coasts. Furthermore such info can also help in establishing guidelines to design marine protected areas and, in the near future, estimate the genetic potential of species to adapt to climate change.[1]